Washington — Carrying the higher-risk genotype for Alzheimer’s disease appears to render even healthy older people subject to major problems with prospective memory, the ability to remember what to do in the future. For the group studied, this could affect important behaviors such as remembering to take medicine at a certain time or getting to a doctor’s appointment. The research appears in the January issue of Neuropsychology, which is published by the American Psychological Association.

People with this genotype have a certain variety, or allele, of a gene called ApoE (for Apolipoprotein E), which switches on production of a protein that helps carry cholesterol in the blood. ApoE has three alleles and about one out of five people carry the e-4 allele. It makes homozygous carriers, who carry this variation on both of their ApoE genes, eight times as likely to develop Alzheimer’s disease as non-carriers. Heterozygous carriers, who carry the high-risk variation only on half the pair, have a three-fold higher risk. Neuro- psychologists have looked at the episodic, or retrospective, memory, of e-4 carriers, especially for recent events. This study was the first to look at their prospective memory.

At the University of New Mexico, a group of 32 healthy, dementia-free adults between ages of 60 and 87 were drawn from a larger study of aging and divided evenly between people with and people without the e-4 allele.

On a task in which participants were asked to remember to write a certain word when they saw a target word, the carriers showed significantly worse prospective memories. Far more often than non-carriers, they failed to remember to write down the desired word when they were supposed to – in other words, they forgot to do what they meant to do, when they meant to do it.